Hirose

If you talk about the famous musician, whose real name is written as 隆 (Takashi) 広 çe¬ (Hirose).
Japanese names are traditionally written in kanji, but you can write her name in hiragana if you really wanted. It would �� (Taka) �� � (Hirose).
According to Japanese Wikipedia, he wrote his name in katakana as タカ (Taka) ヒロ セ (Hirose).

To answer your second question, yes, there are names of Japanese without Kanji; first name is actually �ゆ� Ayumi Hamasaki and not 步. :)